use 0,xED instead of ED#xED in teco.ini
default Scintilla-path is ../scintilla

so no additional --with-scintilla is necessary when building from
a source bundle
replace GNU readlink dependency with custom canonicalize() shell function

 * some build environments (like XCode) do not have a GNU readlink by default
use a Debian version and branch by default

 * distributed binary packages are standard debian packages
 * ./distribute might fix up the package version and branch for Ubuntu/PPA
./distribute debian SIGN=yes: sign source/binary packages